How did Tyrannosaurus Rex become the iconic apex predator of North America 67 million years ago? Paleontologist Dr. Lindsay Zanno is uncovering the answer. Each year she spends several months on expedition, scouring the badlands of western North America in search of clues. Along the way, she has discovered many new species — including some of the earliest predecessors of  T. Rex. Join Dr. Zanno for a fascinating look at how a global climate crisis during the Cretaceous Period changed the course of evolution for this prehistoric tyrant and its ancestors.